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[Abstract]: Due to the proliferation of renewable energy systems, the study of voltage and frequency stability is a crucial aspect. Recently, this problem has been approached from a purely geometrical point of view with interesting results. The present work investigates the properties of the so-called electrical curves described by arbitrary voltage or current vectors in Euclidean spaces. Through the invariants of these curves, certain indices can be constructed to detect abnormal operation or irregular characteristics in electrical power systems. Different scenarios and examples have been solved in this work to support the proposed theory.

[Abstract]: The optimisation of energy consumption requires a reasonably accurate measurement, so an appropriate and advanced monitoring system of the relevant electrical variables in the electrical installations is of paramount importance. In this context, interoperable and highly configurable devices play a crucial role. A clear example is the OpenZMeter (OZM) which is an open source, open hardware, multi-purpose precision smart meter that can measure a wide range of electrical variables at a high sampling rate and provide processed data on power quality. The aim of this work is to show the use and possible applications of the new high sampling frequency data provided by the OZM device, which are much richer and more accurate than those obtained with other low-cost electrical meters. For this purpose, the opensource tool NILMTK has been used and adapted. Likewise, the use of two of the best known and most widely used algorithms such as Combinatorial Optimisation (CO) and the Factorial Hidden Markov Model (FHMM) has been considered, analysing the results obtained in the experimental study and offering a detailed comparison of the performance of the two different disaggregation algorithms using metrics for the different cases, as well as the incorporation of transients, and the comparison with other public Datasets

[Abstract]: The objective of this work is to create a tool that serves to know the possibilities of manufacturing, storage, assembly, and maintenance of floating marine structures trying to take advantage of the ports and shipyards of Spain. This would help reduce costs and could make this type of energy more profitable. To this end, all the Spanish ports and shipyards have been analyzed, considering the characteristics and possibilities of each of them. In the study, those that did not meet certain essential conditions for the manufacture, storage, assembly, and maintenance of power generation equipment have been discarded.

[Abstract]: The objective of this work has been to analyze the variation of different economic parameters (Levelized Cost Of Energy and Internal Rate of Return) for two possible ways of manufacturing: production by project to mass production. For this, 6 possible scenarios have been considered, taking into account the number of equipment manufactured and the economic parameters have been calculated in order to know which alternative provides greater economic viability, thus making the project more profitable.

[Abstract]: Marine renewable energies are being implemented as basic energy sources of the Spanish energy system for various reasons, the first because the planet Earth is made up of 70% water, which makes marine resources very important when programming the production, the second because they are clean energies that do not emit greenhouse gases, necessary to comply with the European Green Deal and the third because this type of energy provides us with energy independence from third countries. But, despite the social benefits mentioned above, we also have to take into account economic factors that can make the economic profitability of this type of equipment less viable. For this, the wind resource, platform costs, etc. are analyzed. Within these factors, this research focuses on seeing how the variation in the price of steel (the main material used in this equipment) caused by the increase in the cost of electricity causes the main economic parameters to vary for a park made up of W2Power hybrid platforms. of 300 MW located on the Atlantic coast of the Iberian Peninsula.

[Abstract]: The aim of this paper is to study the suitability of different floating offshore energy technologies in a particular location in economic terms. In this context, their main initial investments and expenses have been taken into account in order to calculate the economic indicators of the economic feasibility study. These indicators are Internal Rate of Return, Net Present Value and Levelized Cost Of Energy. The case study has evaluated the Canary Islands (Spain) and three types of floating offshore renewable energies: offshore wind, wave energy and hybrid systems. The method created generates economic maps, which facilitates the election of the best area where install offshore renewable energy farms in the location selected. In addition, it also allows to select what is the best marine technology to be exploited in this area.

[Resumen]: El libro “Violencias de género. Persistencia y nuevas formas” cuya edición se ha financiado con fondos del Pacto de Estado Contra la Violencia de Género, recoge investigaciones llevadas a cabo desde ámbitos académicos muy diferentes tales como la filosofía, el derecho, la psicología, la sociología, incluso la arquitectura y, por supuesto, la educación, sobre las distintas formas que toma la violencia contra las mujeres en nuestros días.

[Abstract]: This paper defines a methodology for the economic feasibility analysis of a floating offshore wind farm composed of tensioned leg platforms, which are part of the EU ARCWIND research project. In this context, the phases and subphases of its life-cycle process are considered to deal with aspects such as bathymetry, characteristics of the platforms, distance from the farm to shore, distance from the farm to port and offshore wind speed. All the costs and other external parameters such as capital cost, electric tariff, interest rate, percentage of financing and corporate tax have been analysed to calculate the internal rate of return, net present value, discounted pay-back period and levelized cost of energy of the farm. This work studies a farm composed of TLP offshore wind platforms designed by CENTEC and located at Ribadeo in Spain. Results indicate the costs and the economic feasibility of this platform for deep waters. They indicate that the platform is economically feasible for the location selected.

[Abstract] The appearance of the SARS-CoV-2 pandemic on the world stage has implemented changes in all social activities and, therefore, in teaching at all educational levels. On the one hand, it is argued that the closure of centers and virtual teaching minimizes the risk of contagion and, on the other, this closure implies a reduction in social interactions in the population at ages in which social skills are lower developing. In addition, it is necessary to guarantee that all children and adolescents have access to the necessary means for distance education. This article analyzes the impact of the COVID-19 pandemic during the second, third and fourth waves in Galicia (northwestern region of Spain), where the centers were kept open with strict security protocols, with the aim of evaluating whether the measure of the center closure is a proportionate measure or not. The results obtained show that, at all educational levels, the incidence of infections has been low, as has the appearance of outbreaks of infections related to educational centers, so the damage caused by this measure can be considered uncompensated, with greater health security.

Wind energy resources are subject to changes in climate, so the use of wind energy density projections in the near future is essential to determine the viability and profitability of wind farms at particular locations. Thus, a step forward in determining the economic assessment of floating offshore wind farms was taken by considering current and near-future wind energy resources in assessing the main parameters that determine the economic viability (net present value, internal rate of return, and levelized cost of energy) of wind farms. This study was carried out along the Atlantic coast from Brest to Cape St. Vincent. Results show that the future reduction in wind energy density (2%–6%) mainly affects the net present value (NPV) of the farm and has little influence on the levelized cost of energy (LCOE). This study provides a good estimate of the economic viability of OWFs (Offshore Wind Farms) by taking into account how wind resources can vary due to climate change over the lifetime of the farm

[Abstract] The objective of this paper is to examine the importance of independent arrays in the offshore renewable energy farms. In this context, several scenarios have been contemplated for a floating offshore renewable energy farm: a farm only using floating wave energy; a farm only using floating offshore wind energy; and a farm composed by floating wave energy and floating offshore wind energy installed in independent arrays. The article proposes a method to calculate the main economic parameters and decide their economic feasibility. A hypothetic offshore renewable energy farm located in the Galicia region (Spain) has been studied as case of study. Results show which of the scenarios has the best economic results. This method is worthwhile to compare different floating offshore renewable energy technologies in economic terms and help in the decision making of this new emerging sector that can help to rebuild Europe in the post-pandemic period.

[Abstract] Offshore wind is becoming a new technology to develop a better sustainable world. Its progress is linked to the use of port facilities, where the offshore wind farms can be stored or pre-installed. The aim of this paper is to analyse the storage space availability for ports in terms of being used for the new offshore wind sector. The case of study will be focused on analysing the port facilities in Spain, country with a great offshore wind resource in some specific areas. Results indicate the ports that can be used for the development of offshore wind in Spain. This work is important in order to establish a roadmap of the offshore wind business in Spain, which can repair the economic and social damaged due to SARS-CoV-2 pandemic.

[Abstract] Wind energy resources are subject to changes in climate, so the use of wind energy density projections in the near future is essential to determine the viability and profitability of wind farms at particular locations. Thus, a step forward in determining the economic assessment of floating offshore wind farms was taken by considering current and near-future wind energy resources in assessing the main parameters that determine the economic viability (net present value, internal rate of return, and levelized cost of energy) of wind farms. This study was carried out along the Atlantic coast from Brest to Cape St. Vincent. Results show that the future reduction in wind energy density (2%–6%) mainly affects the net present value (NPV) of the farm and has little influence on the levelized cost of energy (LCOE). This study provides a good estimate of the economic viability of OWFs (Offshore Wind Farms) by taking into account how wind resources can vary due to climate change over the lifetime of the farm.

[Abstract] The aim of this chapter is to examine the offshore wind as a pillar for a new sustainable business. In this context, the chapter firstly analyses the significance of renewable energies. Secondly, it analyses several types of offshore renewable energies, the state of offshore wind energy in Europe, and the projections of offshore wind in the world. Thirdly, it presents an overview of the levelized cost of energy (LCOE), comparing its value for different energy technologies. Moreover, a new concept, called SCOE, is introduced to incorporates society in the LCOE equation. Finally, conclusions talk about the importance of choosing a sustainable way of generating electricity in our future.

[Abstract] The employer (owner) of the project wants to obtain the maximum profit for the money invested and the consultant (contractor) will try to give less for that money. The regulation of their relationship is based on the contractual agreement, which in the energy sector is mainly based on the engineering, procurement, and construction (EPC) model. The objective of this work was to evaluate which factors should be included in the drafting of contracts, to minimize problems between the parties, and thus minimize execution costs and optimize operation and maintenance costs. Information and data on the integration of operability and maintainability criteria in contracts for 158 projects, with a total contract value of close to €40,000M, were analyzed. Several of those projects corresponded to wind, solar, and hydroelectric plants. The information collected the perception of the agents involved, and was classified according to the experience of the agents consulted in the operation and maintenance areas. Finally, the proposed criteria were prioritized. In general, the owner is willing to introduce these criteria in his contracts if they reduce the operation and maintenance cost by around 1–5%, while the contractor is interested in increasing his probability to be selected by

[Abstract] The objective of this work is to establish a framework for the development of an economic analysis tool for floating offshore wind platforms built in concrete. The operation and usefulness of the beta version of a software, called Arcwind, is explained. It calculates the main economic aspects of offshore wind platforms built in concrete considering different locations in the European Atlantic Arc. This software allows the user to select different input parameters such as: the type of platform, the installation area of the farm, its specific location and in this way create different analysis scenarios. This paper analyzes the case study to install TELWIND® offshore concrete floating platforms in the Canary Islands, in Spain. The software provides data on the main economic parameters of the farm, such as Levelized Cost Of Energy (LCOE), Net Present Value (NPV), Internal Rate of Return (IRR), Pay-Back Period (PBP), as well as the main costs: cost of conception and definition, cost of design and development, cost of manufacturing, cost of installation, cost of operation and cost of dismantling. Using these parameters, a first analysis of the viability of this type of floating technology built on concrete is shown.

[Abstract] Light emitting diode (LED) and compact fluorescent light (CFL) lamps are widely used because they are associated with low energy consumption and a reduced environmental impact. In the present paper, a study of the real consumption of these devices has been carried out. To do this, the active, reactive, distortion and apparent power and electrical efficiency for various lamps have been measured and calculated. The distortions produced in the network provoke the consumed energy to be in the order of 50–75% higher than that which appears in the commercial characteristics. This situation means that for its operation, it is necessary to generate and distribute an amount of energy much higher than that which is declared as the consumption of these lamps, and so far, this amount of energy is neither quantified nor invoiced. Additionally, groups of lamps have also been studied to check whether, when working together on the same network, there is a compensation phenomenon that reduces the negative effects of individual lamps. We have found that this compensation effect does not occur for the type of devices evaluated.

[Abstract] The goal of this work is to carry out an economic analysis of a novel floating offshore wind structure, of which the main material is concrete: the SATH® platform. It takes a step forward in floating marine wind energy research, in which traditional platforms are mainly composed of steel. The technique to calculate the costs of the platform and the economic parameters to decide if the farm is economically feasible are explained in the paper. This case study analyzes a possible farm of 500 MW located in Portugal and several scenarios considering different electric tariffs and capital costs (Scenario 1: electric tariff of 50 €/MWh and 6% of capital cost; Scenario 2: electric tariff of 50 €/MWh and 8% of capital cost; Scenario 3: electric tariff of 150 €/MWh and 6% of capital cost; Scenario 4: electric tariff of 150 €/MWh and 8% of capital cost). Results show the economic feasibility of a farm with the characteristics of Scenarios 3 and 4. This work is significant in order to provide a new approach to analyzing traditional floating offshore wind structures, which can represent a path towards the future of floating offshore renewable energy technologies.

[Abstract] The aim of this work is to develop a software to calculate the economic parameters so as to determine the feasibility of a floating offshore renewable farm in a selected location. The software can calculate the economic parameters of several types of offshore renewable energies, as follows: one renewable energy (floating offshore wind—WindFloat, tension leg platform (TLP), and spar; floating wave energy—Pelamis and AquaBuoy), hybrid offshore wind and wave systems (Wave Dragon and W2Power), and combined offshore wind and waves with different systems (independent arrays, peripherally distributed arrays, uniformly distributed arrays, and non-uniformly distributed arrays). The user can select several inputs, such as the location, configuration of the farm, type of floating offshore platform, type of power of the farm, life-cycle of the farm, electric tariff, capital cost, corporate tax, steel cost, percentage of financing, or interest and capacity of the shipyard. The case study is focused on the Galicia region (NW of Spain). The results indicate the economic feasibility of a farm of floating offshore renewable energy in a particular location in terms of its costs, levelized cost of energy (LCOE), internal rate of return (IRR), net present value (NPV), and discounted pay-back period. The tool allows for establishing conclusions about the dependence of the offshore wind resource parameters, the main distances (farm–shore, farm–shipyard, and farm–port), the parameters of the waves, and the bathymetry of the area selected

[Abstract] Reactive power is an important parameter in electrical power systems since it affects the efficiency of the system because it is not useful energy. It decreases the power factor of the system and limits the ability of generators to deliver useful power. It is therefore necessary to understand and correctly measure the phenomenon of reactive energy in three-phase systems. In this paper, we analyze reactive power in linear and unbalanced three-phase systems using the Unified Theory of Electrical Power and the Institute of Electrical and Electronics Engineers Standard 1459-2010 (IEEE Std. 1459-2010) to obtain expressions for reactive power in balanced and unbalanced systems and noting that there are terms that exist only for unbalanced systems. Analysis of the measurements carried out led us to identify the existence of two components of reactive power—that due to reactive elements, and that caused by unbalances in the system. Knowing the causes that generate reactive power, it is possible to act more effectively on the problem and therefore achieve a more sustainable generation of electric power and a lower environmental impact.

[Abstract] This study shows the efects of wear on welded joints of ASTM A355 Gr. P11 “Seamless Ferritic Alloy-Steel Pipe for High Temperature Service” steels subjected to the welding procedures established by codes B31.1 and ASME III. The standard welding procedure establishes the following steps: a preheating process, welding and post-weld heat treatment. This generates a wear behavior that depends on the thermal cycles to which the diferent areas of the joint are subjected. The objective of this article was the study of the behavior against the flow-accelerated corrosion of the welded joints of a low alloy steel. There is the possibility of establishing welding procedures other than those established, while maintaining the safety ranges, depending on the field of application for the steel.

[Abstract] The objective of this paper is to examine the economic aspects of a concrete offshore wind floating platform in the Atlantic Arc of Europe (Portugal and Spain). The life-cycle cost of a concrete floating offshore wind platform is considered to calculate the main economic parameters that will define the economic feasibility of the offshore wind farm. The case of study is the concrete floating offshore wind platform Telwind®, a spar platform with a revolutionary way of installing using a self-erecting telescopic tower of the wind turbine. In addition, the study analyses thirteen locations in Spain and twenty in Portugal, including the Atlantic islands of both countries. Results indicate that the economically feasible location to install a concrete o shore wind farm composed of concrete platforms is the Canary Islands (Spain) and Flores (Portugal).